Process and apparatus for producing alkali metals.



J. BRODE. PROCESS AND APPARATUS FOR PRODUCING'IALKALI METALS.

I APPLICATION FILED JULY 3.1915- 1,258,529.

Wit neoaao: a nue ntoz Jz r/ armm' r'ade 47 9&1; 71 l f attoameg Patented Mar. 5, 1918'.

UNITED STATES PATENT OFFICE.

JOHAN'NES BRODE, OF LUD'WIGSI-IAFEN-ON-THE-RHINE, GERMANY, ASSIGNOR TO BADISGHE ANILIN &, SODA FABBIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GER- MANY, A CORPORATION OF BADEll'.

PROCESS AND APPARATUS FOR PRODUCING ALKALI METALS.

Application filed July 3, 1915.

To all whom it may concern:

Be it known that I, JOHANNEs Bnoon, citizen of the German Empire, residing at Ludwigshafen-on-the-Rhine, Germany,have invented new and useful Improvements in Processes and Apparatus for Producing Alkali Metals, of which the following is a specification.

The electrolytic decomposition of fused alkali haloids offers great difiiculties owing to the circumstance that both the free halogen and the alkali metal formed by the electrolysis rise to the surface of the melted salt and have a great tendency to recombine. It is, therefore, necessary to separate the products formed at the anode and at the cathode by partitions which must be adapted to withstand, at a comparatively high temperature, the attack of the alkali metal on the one hand and that of the free halogen on the other hand.

It has been heretofore attempted to overcome these difliculties by employing two diaphragms consisting of two different materials, that on the anode side being permanent against free halogen, that on the oathode side being capable of withstanding the alkali metal, or by covering the wall with a layer of solidified melt by cooling the said wall.

It has now been found that the aforesaid difficulties can be overcome while employing a single partition or wall consisting of metal, and without cooling this wall, by taking care that the partition on the anode side is during the electrolysis permanently covered with melted salt. For this purpose the wall can continuously be irrigated with the melted salt or, What is still more simple, the arrangement is made in such manner that the surface of the melt in the anode space is higher than the highest point of the wall, so that the latter is completely dipped into the melted salt. In the latter case the alkali metal which is formed during the electrolysis collects below the wall and can be withdrawn by an outlet leading from the highest point of the cathode space downward through this space or laterally through the cell. As on the one hand the melt in the anode space is to be kept permanently at such height that the wall is completely dipped into the melt, on the other hand the alkali metal must'run off continuously, the

Specification of Letters Patent.

Serial No. 37,631.

compartment into which the evolved halogen escapes, is kept under a pressure which is somewhat lower than that of the compartment into which the metal runs, or the outlet for the metal is elevated outside the cell to such a degree that a sufiicient layer of molten metal is formed upon the melted salt so thatthe metal runs offeven if the two compartments are under the same pressureonly by the increase of the layer of the molten metal.

It is sutficient to use a metallic and tight wall only at the place where the alkali metal is collected. The wall, however, can dip farther into the melt, and in this case the wall in its upper part may be tight, in its lower part perforated 0r consist of wire netting. It is preferable to arrange the electrodes lower than the tight wall so that the electric current, or. the greatest part thereof, flows directly from the anode to the cathode and that, therefore, no currentor if anya very weak current passes through the walls as bi-polar electrodes. Even that part of the-current which may pass through the tight wall does not destroy it but will only redissolve small quantities of the alkali metal which, during the operation, is present below the said wall.

In the accompanying drawing a construction of an apparatus according to the invention is shown, the sketch being a cross section through the electrolytic cell.

Into the electrolytical cell C the anodes A and the cathodes K are introduced. The anode space is separated from the cathode space by a metallic wall, the upper part- T of which is tight, while the lower part T is perforated. The alkali metal formed is removed by the pipe M reaching up to the top part of the wall. The free halogen evolved in the anode space escapes through the outlet H. During the operation, melted alkali haloid, such as melted common salt, is filled into the cell until it completely covare the wall at the anode side, e. 9. until the surface of the melt stands at N,. The melt is maintained at this elevation by keeping the pressure at H somewhat lower than the pressure in the compartment into which the metal is running through M, so that the melt in the anode space rises to N,, while in the cathode space it only rises to N Various modifications may be made in this apparatus as the invention is in no way confined to the above description or the accompanying drawing.

Now what I claim is:

1. The process of producing alkali metal by electrolysis of fused alkali haloid, which consists in separating the products formed at the anode and cathode, covering the separating means on the anode side with fused alkali haloid, and drawing off the halogen evolved in the anode space and the alkali metal formed in the cathode space.

2. The process of producing alkali metal by electrolysis of fused alkali haloid which consists in dipping into a vessel, containing the anodes and the molten electrolyte, a me- I covered by fused alkalivhaloid, and drawing off the alkali metal formed from the cathode space, and the halogen evolved in the anode space under lower pressure than the metal.

4:. An apparatus for the production of alkali metal by electrolysis of fused'alkali haloid, comprising a cell provided with anodes and cathodes, a metallic partition henatatae having a closed top and being arranged at such an elevation that during the electrolysis it is completely covered by the molten electrolyte and means for drawing off the halogen under'lower pressure than the metal.

6. An apparatus for the production of alkali metal by the electrolysis of fused alkali haloid, comprising a cell provided with anodes and cathodes, a metallic partition between the anodes and cathodes, said partition having a closed top above the oathodes and a perforated base located opposite the electrodes and being arranged at such an elevation that during the electrolysis it is completely covered by the molten electrolyte and means for drawing ofl the products.

in testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

JOHANNES BRODE.

Witnesses ARTHUR Dnnonvrnnn, FRIEDRICH KLmNY. 

